108 lines
3.0 KiB
Python
Executable File
108 lines
3.0 KiB
Python
Executable File
# Twitter's Snowflake algorithm implementation which is used to generate distributed IDs.
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# https://github.com/twitter-archive/snowflake/blob/snowflake-2010/src/main/scala/com/twitter/service/snowflake/IdWorker.scala
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import time
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from server.settings import SNOW_DATACENTER_ID, SNOW_WORKER_ID
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class InvalidSystemClock(Exception):
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"""
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时钟回拨异常
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"""
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pass
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class Constant(object):
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# 64位ID的划分
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WORKER_ID_BITS = 5
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DATACENTER_ID_BITS = 5
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SEQUENCE_BITS = 12
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# 最大取值计算
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MAX_WORKER_ID = -1 ^ (-1 << WORKER_ID_BITS) # 2**5-1 0b11111
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MAX_DATACENTER_ID = -1 ^ (-1 << DATACENTER_ID_BITS)
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# 移位偏移计算
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WOKER_ID_SHIFT = SEQUENCE_BITS
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DATACENTER_ID_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS
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TIMESTAMP_LEFT_SHIFT = SEQUENCE_BITS + WORKER_ID_BITS + DATACENTER_ID_BITS
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# 序号循环掩码
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SEQUENCE_MASK = -1 ^ (-1 << SEQUENCE_BITS)
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# Twitter元年时间戳
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TWEPOCH = 1288834974657
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class IdWorker(object):
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"""
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用于生成IDs
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"""
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def __init__(self, datacenter_id, worker_id, sequence=0):
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"""
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初始化
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:param datacenter_id: 数据中心（机器区域）ID
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:param worker_id: 机器ID
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:param sequence: 起始序号
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"""
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# sanity check
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if worker_id > Constant.MAX_WORKER_ID or worker_id < 0:
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raise ValueError('worker_id值越界')
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if datacenter_id > Constant.MAX_DATACENTER_ID or datacenter_id < 0:
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raise ValueError('datacenter_id值越界')
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self.worker_id = worker_id
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self.datacenter_id = datacenter_id
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self.sequence = sequence
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self.last_timestamp = -1 # 上次计算的时间戳
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def _gen_timestamp(self):
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"""
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生成整数时间戳
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:return:int timestamp
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"""
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return int(time.time() * 1000)
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def get_id(self):
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"""
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获取新ID
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:return:
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"""
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timestamp = self._gen_timestamp()
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# 时钟回拨
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if timestamp < self.last_timestamp:
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raise InvalidSystemClock
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if timestamp == self.last_timestamp:
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self.sequence = (self.sequence + 1) & Constant.SEQUENCE_MASK
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if self.sequence == 0:
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timestamp = self._til_next_millis(self.last_timestamp)
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else:
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self.sequence = 0
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self.last_timestamp = timestamp
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new_id = ((timestamp - Constant.TWEPOCH) << Constant.TIMESTAMP_LEFT_SHIFT
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) | (self.datacenter_id << Constant.DATACENTER_ID_SHIFT) | \
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(self.worker_id << Constant.WOKER_ID_SHIFT) | self.sequence
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return new_id
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def _til_next_millis(self, last_timestamp):
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"""
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等到下一毫秒
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"""
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timestamp = self._gen_timestamp()
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while timestamp <= last_timestamp:
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timestamp = self._gen_timestamp()
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return timestamp
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idWorker = IdWorker(SNOW_DATACENTER_ID, SNOW_WORKER_ID)
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if __name__ == '__main__':
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print(idWorker.get_id())
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